The use of intravascular medical devices and implants has become an effective method for treating many types of vascular disease. In general, a suitable intravascular device is inserted into the vascular system of the patient and navigated through the vasculature to a target site in a patient. Using this method, virtually any target site in the patient's vascular system may be accessed, including the coronary, cerebral, and peripheral vasculature.
Catheters are often utilized to place medical implants, such as stents and embolic devices, at a desired location within the body. A medical implant may be loaded onto a catheter in a configuration having a reduced diameter and then introduced into the lumen of a body vessel. For example, self-expanding stents are to be delivered in an elastically compressed state while being confined within a tubular restraining member, and then allowed to elastically expand into engagement with the interior of the body vessel when removed from the tubular restraining member. Once delivered to a target location within the body, the expanded and enlarged stent configuration supports and reinforces the vessel wall while maintaining the vessel in an open and unobstructed condition.
Various types of delivery systems are used in a number of intravascular applications for delivering self-expanding stents, such as the so-called “over-the-wire” and “rapid-exchanged” delivery systems. In the “over-the-wire” delivery system, a catheter is introduced into the patient over a guidewire which has been previously introduced; the guidewire extends through the entire length of the catheter through a lumen of the catheter. In the “rapid-exchange” delivery system, the guidewire extends through only a distal portion of the catheter from the distal tip to a guidewire port located proximal of the distal tip. In the “over-the-wire” and “rapid-exchanged” delivery systems, stents are loaded and confined within the inner wall of a catheter narrowing the lumen defined by the inner wall of the catheter and reducing its flushing capabilities. Further, stents confined within the inner wall of the delivery catheters are coaxially disposed over the guidewire, which alters the guidewire position during delivery of a stent.
Therefore, there is an ongoing need to provide an implant delivery system for delivering a self-expanding stent that facilitates flushing capabilities and minimize alteration of the guidewire position during stent deployment.